Magnetic impulse generator



April 18, 1967 J. N. BARR 3,315,104

MAGNETIC IMPULSE GENERATOR Filed April 16, 1964 United States Patent Ofilice 3,3 l5,l4 Patented Apr. 18,. 1967 3,315,104 MAGNETIC IMPULSE GENERATOR John N. Barr, Detroit, Mich., assignor to Square D Cornpany, Park Ridge, 111., a corporation of Michigan Filed Apr. 16, 1964-, Ser. No. 360,346 3 Claims. (Cl. 310-29) This invention relates to devices for providing voltage pulses and more particularly to an impulse voltage generator suitable for selectively switching transistorized logic elements in static control systems.

Transistorized logic elements are being used in electrical control systems to an increasing degree because of their inherent reliability, absence of moving parts, fast switching time, small size, and other advantages. The transistorized logic circuitry of such systems is conventionally controlled by the application of voltage pulses of a given magnitude and polarity to the inputs of the various logic elements to selectively control the functions thereof either singularly or in various combinations.

Previously such voltage pulses usually have been sup plied by completing a circuit from a source of voltage to the input of a logic element through a conventional contactnnaking device such as a push-buttou or limit switch. Such contact-making devices inherently prevent a so-called static control system from being, in fact, truly static. Impulse voltage generators are, of course, known in the art and have been used in various applications. The prior impulse voltage .generators, however, have been found to be either too complicated or incapable of providing the uniform voltage pulses required for reliable control transistorized logic circuitry A more specific object is the provision of a magnetic impulse voltage generator having a double-armed armature pivoted about its central axis between a pair of pole in static control systems.

uniform voltage the pole pieces.

Other objects and advantages of this invention will become apparent from the following specification wherein reference is made to the drawings, in which:

FIG. 1 is a perspective view of a magnetic impulse with the invention;

FIG. 2 is a perspective view of the impulse generator of FIG. 1 with the cover of the housing removed;

FIG. 3

conventional flip-flop circuit. In practicing the invention, vided within which there is a magne-tizable base having a A permanentamagnet extends upwardly from a central por- Upon selective depression of one of the push-buttons, the operating bar is pivoted to make contact with the armature to cause one of the armature arms to separate from its associated one of the pole pieces and the other armature arm to engav e its associated one of the pole pieces. Upon such engagement, the reluctance of the magnetic circuit including the engaged pole piece is reduced and the resultant increase in magnetic flux therethrough induces a voltage impulse in the coil on the engaged pole piece. Likewise, subsequent depression of the other push-button causes the operating bar to pivot in the opposite direction whereby contact is made with the armature to cause said one armature arm to re-engage its associated pole piece while said other armature arm disengages from its associated pole piece. This results in a voltage pulse being induced in the coil associated with the engaged pole piece. The armature operates with a snap-action due to the magnetic attraction of the permanent magnet when either of the armature arms nears its associated pole piece so that the speed of the armature at the moment of impact with the pole piece is rapid and uniform. This rapid and unifonm movement produces voltage pulses of a uniform magnitude independent of the force applied to the push-buttons.

Referring now to FIGS. 1 and 2 of the drawings, the magnetic impulse voltage generator 10 includes a housing 11 having a base 11a with upright end portions and also having a U-shaped cover 11b. provided with openings through which respective push-buttons 12r and 13 extend. It will be understood that other rectilinearly movable operating means, such as limit switch operators, may be substituted for the push-buttons 12 and 13 or other operating means may be arranged to reciprocate the push-buttons 12 and 13. A base plate 14 of a magnetizable material is fastened to the base 11a as by screws 14a and supports pole pieces 15 and 16 at respective opposite ends which are attached to the base plate 14 by any suitable means. The pole pieces 15 and 16 are surrounded by respective coils 17 and 18. The coil 17 has erminals 17a and 17b and the coil 18 has terminals 18a and 18b.

A magnet means comprising a permanent magnet 19, preferably made of ceramic material, and a spacer bar 20 of magnetizable material is positioned on a central portion of the base plate 14 between the pole pieces v15 and 16. The magnet 19 supports the spacer bar 20 and an armature 2 1 is pivotally supported on the spacer bar 20 and held thereon by a pair of screws 22 (only one is shown), each having a head portion 22a loosely overlapping an edge portion of the armature 21. The screws 22 pass loosely through holes provided in the spacer bar 20 and afiix the armature 21, the. spacer bar 20 and the magnet 19 as into respective threaded openings provided in the base plate 14. The armature 21 is of a slight V-shape con figuration to permit it to pivot about its central transverse 15 and 16, is effected by selective depression of the push-buttons 12 and 13,

A U shaped support bracket 30 is provided having tongue portions 30:: and 3012 at opposite ends which rest on respective inwardly extending lip portions 31 and 32 of the base 11a and are fastened thereto by screws 33 The push-button 12 comprises a cylindrical top portion 12a and a rectilinear body portion 12b from which a flat push-button 13 comprises a cylindrical top port-ion 13a and a rectilinear body portion 13b from which a fiat tongue portion extends downwardly. The body portions 1% and 13b slidably extend throughopenings 35 and 36, respectively, in the support bracket 30. An

operating lever 37 is pivotally connected at its opposite ends, respectively, to the tongue portions 12c and 13c by screws 38 and 39 and is pivotably attached at its central portion to an L-shaped bracket 40 as by a screw 41. The bracket 40 is in turn attached to the support bracket 30 by screws 42. A resilient helical spring 43 surrounds the body portion 12b of the push-button 12 and bears against the bottom surface of the cylindrical portion 12a and the top surface of the support bracket 30. Likewise, a resilient helical spring 44 surrounds the body portion 13b of the push-button 13 and bears against the bottom surface of the cylindrical portion 13a and the top surface of the support bracket 30.

The impulse voltage generator may be used to control a wide variety of logic elements employed in static control systems such as AND, OR, NOR, MEMORY and NOT elements. It is to be understood, however, that the generator 10 may be utilized in any application where uniform voltage pulses are needed.

For illustrative purposes, the impulse generator 10 is shown in FIG. 3 as controlling a flip-flop circuit 50 comprising a pair of transistorized NOR logic elements 51 and 52. The NOR element 51 includes a pair of inputs 51 and 51b and an output 51c while the NOR element 52 includes a pair of inputs 52a and 52b and an output 521:. The output 51c of the NOR element 51 is connected to the input 52b of the NOR element 52 and the output 520 of the NOR element 52 is connected to the input 51b of the NOR element 51. The output 510 may be considered as the output of the flip-flop circuit 50. The operation of the logic flip-flop circuit 50 is well known in the art so that detailed description is not necessary. An individual NOR element is characterized by the fact that there is an output or one signal only when there is an absence of a control or one signal on all of its inputs. Presence of a one signal of a given polarity and magnitude on any of the inputs of a NOR element changes the output thereof to zero.

To operate the circuit 50, the output of the coil 17 is used to control the NOR element 52 over a supply lead 54 connected between the terminal 17a and the input 520, while the output of the coil 18 is used to control the NOR element 51 over a supply lead 55 connected between the terminal 18a and the input 51a. The coil terminals 17b and 18b are grounded as indicated, and the NOR flip-flop circuit 50 includes an internal ground (not shown) for circuit continuity.

Initially the armature 21 may be assumed to be in the position of FIG. 3, wherein the arm 21b is in engagement with the pole piece 16. It may be further assumed that there is a zero signal at the output 510. With the armature 21 in this position, the magnetic flux produced by the magnet 19 is substantially contained in a magnetic loop defined by the base plate 14, the pole piece 16, the armature arm 21b and the spacer bar 20 as shown by the arrows in FIG. 3. When a downward force is applied to the push-button 12, the tongue portion 12c is moved into engagement with the armature arm 21a and imparts a pivoting motion to the armature 21 in the counterclockwise direction so that the armature arm 21b disengages from the pole piece 16 and the armature 21 continues to pivot until the arm 21a engages the pole piece 15. The magnetic flux is thereupon diverted from the loop previously described to a second loop defined by the base plate 14, the pole piece 15, the armature arm 21a and the spacer bar 20. The magnetic lines of flux that thereby cut the coil 17 induce a voltage pulse therein which appears at the input 52a of the NOR element 52. This voltage pulse may be considered as a one signal. A one signal at the input 52a of the NOR element 52 causes the output 52c to change to zero." Since there is now an absence of control signal on each of the inputs 51a and 51b of the NOR element 51, there is an output, or one signal, at the output 51c. This may be designated as the ON condition for the NOR logic flip-flop circuit 50.

After the armature 21 has been moved to the position described above, a downward force applied to the pushbutton 13 causes the armature arm 21a to disengage from the pole piece 15 and the armature arm 21b to engage the pole piece 16. The resultant shift in flux through the coil 18 produces a voltage pulse therein, which then appears at the input 51a of the NOR element 51 causing the output 510 to go to zero. The logic circuit 50 is then in the OFF condition.

It should be apparent that the speed of movement of the armature 21 will be substantially uniform regardless of the force applied to the push-buttons 12 and 13. When the push-button 12 strikes the armature arm 21a as a result of its downward movement, the armature 21 is pivoted in a counterclockwise motion toward the pole piece 15. However, the movement of armature 21 is also magnetically assisted by the flux of the magnet 19. This magnetic attraction controls when the armature arm 21a nears the pole piece 15 and insures a substantially uniform speed of movement at the instant of engagement therewith to provide a substantially uniform voltage impulse in coil 17. In like manner, substantially uniform voltage impulses are induced in the coil 18 when the armature arm 21b is moved into engagement with the pole piece 16.

It should further be apparent that, although a voltage pulse of a given polarity will appear at the output terminal of the coil associated with the pole piece being engaged by the armature 21, a voltage pulse of the opposite polarity will simultaneously appear at the output terminal of the coil associated with the pole piece being disengaged by the armature 21. For example, if the terminal 17a of the coil 17 is assumed to be rendered negative with respect to the terminal 17b when the armature 21 engages pole piece 15, then the output terminal 18a of the coil 18 will be rendered positive with respect to the terminal 18b when the armature leaves the pole piece 16. In the same manner, the output terminal 17a will be rendered positive with respect to the terminal 17b when the armature 21 leaves the pole piece 15. In some instaces, pulses of one of the two polarities may be undesirable. In such case, diodes 56 and 57 may be employed to suppress these undesired pulses. The diode 56 is connected across the terminals 17a and 17b while the diode 57 is connected across the terminals 18a and 1812. In the embodiment shown, the diodes 56 and 57 are poled to provide a low impedance path to ground for positive pulses appearing at the terminals 17a and 18a, respectively. It is to be emphasized, however, that the diodes 56 and 57 may not always be necessary. This is because the positive pulses resulting from the disengagement of the armature 21 from the pole pieces 15 and 16 are somewhat lower in magnitude than the negative pulses produced by the engagement of the armature 21 with the pole pieces 15 and 16. In the embodiment of the invention described herein for controlling the transistorized NOR logic flip-flop circuit 50, the diodes 56 and 57 have been found not to be necessary.

I claim:

1. A magnetic impulse generator comprising a magnetizable core means having spaced protruding first and second magnetizable pole pieces, coil means surrounding said core, a permanent magnet means mounted in fluxconducting relation on said core means intermediate said pole pieces, a magnetizable armature pivotably supported intermediate its end portions on said permanent magnet means, said end portions overlying the exposed end faces of said pole pieces, respectively, with one of said end portions spaced from its associated end face while the other of said end portions is in engagement with its associated end face in one of two turned positions of said armature about its pivot and with said other end portion in engagement with its associated end face and said one end portion spaced from its associated end face in another turned position of said armature about its pivot, an operator means operable to rock said armature about its pivot to eifect said engagement with said pole pieces, selectively, said operator means including a pivotably supported operating lever having push button means attached at its opposite ends, respectively, said operating lever being spacially aligned with said armature in a manner such that selective depression of said push-button means pivots said operating lever into contact With said armature so as to impart said rocking motion thereto, engagement of said armature with a pole piece causing the reluctance of the magnetic loop including said core means and the one of said pole pieces being engaged to be suddenly reduced thereby inducing a voltage impulse in said coil means, and said rocking motion of said armature being magnetically assisted to cause substantially uniform acceleration of said armature independently of the speed of said operator means in the region of close proximity thereof to the one of said pole pieces being engaged.

2. A magnetic impulse generator in accordance with claim 1 characterized in that said coil means comprises a pair of coils and said coils surround said outer legs, respectively.

3. A magnetic impulse generator in accordance with References Cited by the Examiner UNITED STATES PATENTS 1,708,095 4/ 1929 Hubbell 310-36 2,784,327 3/ 1957 Drescher 310-36 2,881,365 4/1959 Bernstein 317-171 2,941,130 6/1960 Fischer et al 3'17-171 2,975,341 3/1961 Schuessler et al. 317-197 X 3,125,652 3/ 1964 Richert ZOO-93.3

FOREIGN PATENTS 953,366 11/1956 Germany.

MILTON O. HIRSHFIELD, Primary Examiner. D. F. DUGGAN, Assistant Examiner. 

1. A MAGNETIC IMPULSE GENERATOR COMPRISING A MAGNETIZABLE CORE MEANS HAVING SPACED PROTRUDING FIRST AND SECOND MAGNETIZABLE POLE PIECES, COIL MEANS SURROUNDING SAID CORE, A PERMANENT MAGNET MEANS MOUNTED IN FLUXCONDUCTING RELATION ON SAID CORE MEANS INTERMEDIATE SAID POLE PIECES, A MAGNETIZABLE ARMATURE PIVOTABLY SUPPORTED INTERMEDIATE ITS END PORTIONS ON SAID PERMANENT MAGNET MEANS, SAID END PORTIONS OVERLYING THE EXPOSED END FACES OF SAID POLE PIECES, RESPECTIVELY, WITH ONE OF SAID END PORTIONS SPACED FROM ITS ASSOCIATED END FACE WHILE THE OTHER OF SAID END PORTIONS IS IN ENGAGEMENT WITH ITS ASSOCIATED END FACE IN ONE OF TWO TURNED POSITIONS OF SAID ARMATURE ABOUT ITS PIVOT AND WITH SAID OTHER END PORTION IN ENGAGEMENT WITH ITS ASSOCIATED END FACE AND SAID ONE END PORTION SPACED FROM ITS ASSOCIATED END FACE IN ANOTHER TURNED POSITION OF SAID ARMATURE ABOUT ITS PIVOT, AN OPERATOR MEANS OPERABLE TO ROCK SAID ARMATURE ABOUT ITS PIVOT TO EFFECT SAID ENGAGEMENT WITH SAID POLE PIECES, SELECTIVELY, SAID OPERATOR MEANS INCLUDING A PIVOTABLY SUPPORTED OPERATING LEVER HAVING PUSH-BUTTON MEANS ATTACHED AT ITS OPPOSITE ENDS, RESPECTIVELY, SAID OPERATING LEVER BEING SPACIALLY ALIGNED WITH SAID ARMATURE IN A MANNER SUCH THAT SELECTIVE DEPRESSION OF SAID PUSH-BUTTON MEANS PIVOTS SAID OPERATING LEVER INTO CONTACT WITH SAID ARMATURE SO AS TO IMPART SAID ROCKING MOTION THERETO, ENGAGEMENT OF SAID ARMATURE WITH A POLE PIECE CAUSING THE RELUCTANCE OF THE MAGNETIC LOOP INCLUDING SAID CORE MEANS AND THE ONE OF SAID POLE PIECES BEING ENGAGED TO BE SUDDENLY REDUCED THEREBY INDUCING A VOLTAGE IMPULSE IN SAID COIL MEANS, AND SAID ROCKING MOTION OF SAID ARMATURE BEING MAGNETICALLY ASSISTED TO CAUSE SUBSTANTIALLY UNIFORM ACCELERATION OF SAID ARMATURE INDEPENDENTLY OF THE SPEED OF SAID OPERATOR MEANS IN THE REGION OF CLOSE PROXIMITY THEREOF TO THE ONE OF SAID POLE PIECES BEING ENGAGED. 